A 3GPP Long Term Evolution (LTE) network is a cellular network that consists of cells managed by base stations. The cells are typically associated with a particular geographic location. A user equipment (UE) located at a particular cell can use the cellular network by transmitting and receiving data to a base station (e.g., an eNodeB) that manages the cell. The UE may communicate with the base station using wireless signals associated with different frequency bands, with each frequency band being associated with a component carrier. For example, a UE and a base station typically communicate signaling data (e.g., radio resource control (RRC)) using a primary component carrier, and communicate other data using a secondary component carrier provided by the base station. When a single secondary component carrier is used for data communication, the data rate can be limited by the bandwidth of the single secondary component carrier frequency band. Radio resources can also become underutilized when other idle secondary component carriers are not used for the data communication.
To achieve high data rate required of LTE, 3GPP specification (TS 36.300 V10.12.0 Sections 5-7) proposes carrier aggregation (CA) as a method to solve the cell edge throughput problem. Under this scheme, a plurality of secondary component carriers can be aggregated for data communication for a particular UE, such that the UE can transmit data using the plurality of secondary component carriers. For example, two or more component carriers can be aggregated and a maximum aggregated system bandwidth of 100 MHz can be achieved with 1 PCC and 2 secondary component carriers.
With such an arrangement, the bandwidth of the wireless frequency band provided for data communication can be extended, leading to an improvement in the data rate. However, under the CA specification of 3GPP (e.g., TS 36.300 V10.12.0 Section 5.5), the determination of allowing an UE to use a secondary component carrier for data transmission does not take into account the load for that secondary component carrier (e.g., a number of UEs scheduled to use that carrier). Also, under current technologies, the determination also does not take into account the traffic load at the core network, nor the effect of downlink interference (e.g., caused by a neighboring base station) at the UE.
The inventors here have recognized several technical problems with such a method, as explained below. First, without taking the load for a secondary component carrier into consideration, there can be both overloading and underutilization the secondary component carriers as a result of carrier aggregation, when some of the secondary component carriers are heavily used by the UEs, while some of the secondary component carriers are idle. Second, without taking the traffic load at the core network (from which a base station receives data for transmission to the UEs) into consideration, it does not provide a mechanism for the base station to aggregate more secondary component carriers (when they are available) to increase the bandwidth available for transmitting the data received from the core network to the UEs. As a result, there can be excessive packet drops at the ingress port of that base station, because the base station cannot transmit the dropped packets to the UEs, leading to poor utilization of radio resources and poor network efficiency. Third, without taking the effect of downlink interference at an UE, it does not provide a mechanism to adjust the aggregation of secondary component carriers for that UE based on the interference, leading to high data error rate and poor network efficiency.